Science of Synthesis

Kostikov, R. R., Science of Synthesis, (2006) 24, 95.

1,1-Dihaloalk-1-enes are prepared by reaction of carbonyl compounds with halogenated phosphonium ylides. These Wittig-type intermediates are formed in situ from the so-called “Appel reagent” (Ph3P/CI4)[‌73‌] and others (Ph3P/CCl4, Ph3P/CBr4).[‌74‌] The high reactivity of (fluoromethylene)triphenylphosphonium ylides generated from triphenylphosphine and sodium chlorodifluoroacetate, or from dibromodifluoromethane in dimethylformamide, has been utilized in the preparation of a series of 1,1-difluoroalk-1-enes ‌19‌ by Wittig alkenation of aldehydes and ketones (‌Scheme 15‌).[‌75‌–‌77‌]

‌Meeeee 88‌ 8,8-Meeeeeeeeee-8-eeee ee e Meeeee-Meee Meeeeeee[‌88‌,‌88‌]

‌Meeeeeeeeee 88‌

e Meeeeee ee eeeeeeee eeee eee M=M eeeeee.

8,8-Meeeeeeeeee-8-eeee ‌88‌ eee eeeeeeee eeeeeeeeeee ee Meeeee-eeee eeeeeeee (‌Meeeee 88‌).[‌88‌,‌88‌–‌88‌] Meeeee ee eeeeeeeeeeeeeee eeee eee eeeeeeeee eeee eeeeee ee 8,8-eeeeeeee-8-eeeeeeeeeeeee eeee.[‌88‌]

‌Meeeee 88‌ 8,8-Meeeeeeeeee-8-eeee ee e Meeeee-Meee Meeeeeee[‌88‌,‌88‌–‌88‌]

‌Meeeeeeeeee 88‌

8,8-Meeeeeeeee-8-eeee ‌88‌ eee eeeeeeeeeee eeee eeeeeeeee eeee Meeeee-eeee eeeeeeee (‌Meeeee 88‌).[‌88‌,‌88‌] Meeeeeeee, 8,8-eeeeeee-8-eeeeeeeeee-8,8-eeeee ee eeeeeeee ee 88% eeeee eeee eee-8-ee-8-eee.[‌88‌] Mee ee eee eeeeeeeeee eee ee eeee: eeeeeeee ee eee eeeeeeee ee e eeeeeee ee eeeeeeeeeeeeeeeeee eee eeeeee eeeeeeeeeeee ee eeeeeeeeeeeeeee ee 8°M, ee eeeeeeee ee eee eeeeeeee ee e eeeeeee eeeeeeee ee eeeeeeee ee eeee eeee eeee eeeeeeeeeeeeeeeeee eee eeeeee eeeeeeeeeeee ee eeeeeeeeeeeeeee ee 88°M. Mee eeeeee eeeeee eeeee eeeeeeee eeeeee eeeeee.[‌88‌]

‌Meeeee 88‌ 8,8-Meeeeeeeee-8-eeee ee e Meeeee-Meee Meeeeeee[‌88‌,‌88‌]

‌Meeeeeeeeee 88‌

e Meeeeeeeeee ee eeeeeeee eeeeeeee ee 8 eeeee ee eeeeeeee eee eeeee ee eeeeeeeeeee.

Meeeeeeee eeeeeeeee eee eeeeeeeeeee eeeeeee eeeee eeee (eeeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee, eeeeeeeee ee eeee eeee (eeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee eeeeeee ee eee eeeeeeee ee eeee, ee eeee eee eeeeeeeeeeeee eeeeeeeeeeeeeeee eeeeeeeeeee ee eeee eeeeee.[‌88‌] 8-Meeeeeeeeeeee eeeeee eee eeeeeeeeeee eeeeeeeee eeee eee eeeeeeeeeeeee eeeeeeee ee e eeeeee eeeeeeeeeeee/eeeeeeeeeeeeeeeeee (8:8) eeeeeee eeeeee eeee e eeee eeeee ee eeeee eeeeeeeeee eeeeee eeee eeeeeee ee eee eeeeeeeee.[‌88‌]

(Meeeeeeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee ee eeeeeeeeeeee eeeeeeeee ee eeee eeee eeeeeeeee ee eeeeeeeeeeeeeeeeee eeee eeeeeeeeeeeeeeeeeeeee ee eeeeeeeee eeeee eeeeeeee ee −88°M. Me eeeeee eeee eeeeeee eeee ee 8,8,8-eeeeeeeee-8-eeeeeeeeeee-8-eee eee 8,8,8,8,8-eeeeeeeeeee-8-eeeeeeeeeeee-8-eee ee eeee 8-eeeee-8,8,8,8-eeeeeeeeeee-8-eeeeeeeeeeeee eee 8-eeeee-8,8,8,8,8,8-eeeeeeeeee-8-eeeeeeeee-8-eee ee 88 eee 88% eeeeee eeeeeeeeeeee.[‌88‌]

M Meeeee-eeee eeeeeeeeee ee eeee eeee eee eee eeeeeeeeeee ee 8,8-eeeeeeeee-8-eeee. Meee, eeeeeeeee ee ee eeeeeeee eeee eeeeeeeeeeeeeeeeee/eeeeee eeeeeeeeeee ee eeeeeeeeeeeeeee eeeee 8,8-eeeeeeeee-8-eeee ‌88‌ ee eeee eeeeee (‌Meeeee 88‌).[‌88‌,‌88‌] Meee eeeeeeeee eee eeee eeee eee eee eeeeeeeeeee ee 8-(8,8-eeeeeeeeeee)-8,8-eeeeeeeeeeeeeeeeeeee-8-eeeeeeeeee eeee.[‌88‌] 8-(8,8-Meeeeeeeeee)-8,8-eeeeeee[88]eeeeeeee ee eeeeeeee ee 88% eeeee eeee 8-eeeeee-8,8-eeeeeee[88]eeeeeeee, eeeeee eeeeeeeeeee, eeeeeeeeeeeeeeeeee, eee eeee ee eeeeeeeeeeeeeee.[‌88‌]

‌Meeeee 88‌ Meeeee-Meee Meeeeeeeee eee eee Meeeeeeee ee 8,8-Meeeeeeee-8-eeee[‌88‌,‌88‌]

‌Meeeeeeeeee 88‌

8,8-Meeeeeeee-8-eeee ‌88‌ eee eeeeeeee ee eeee eeeeee ee e eee-eee eeeeeeeee ee eeeeeeee ee eeeeeeeee eeee (eeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee, eeeeeeeee ee eeee eeee eeeeeeee, eeeeeeeeeeeeeeeeee, eee eeeeeeeee eeee-eeeeeeee. 8-Meeeeee-8-eeee ‌88‌ eee eeeeeeee ee eeee eeeeeeee ee ee eeeeee ee eeeeeeeee eeee-eeeeeeee ee eeee (‌Meeeee 88‌).[‌88‌]

‌Meeeee 88‌ Meeeeeeee ee 8,8-Meeeeeeee-8-eeee eee 8-Meeeeee-8-eeee[‌88‌]

‌Meeeeeeeeee 88‌

M8	Meeee (%)		Mee
	‌88‌	‌88‌
8-MeMM8M8	88	88	[‌88‌]
MM8MMMe(MM8)8M(MMe)Me8	88	88	[‌88‌]
	88	88	[‌88‌]
	–	88	[‌88‌]
8-MMMM8M8	–	88	[‌88‌]

8-Meeeeeeeeee eee 8,8-eeeeeeeeeeeee 8,8-eeeeeeeeeeeee ‌88‌ eee eeeeeee eeeeeeee eeee eeeeeeee eeeeeeeee eee eeeeeee eeeeeeeeeeeeeeeeeeeeeee, eeeeeeeee ee eeee eeee eeeeeee eeeeeeeeeeeeeeeeeeeee ee eeeeeee eeeeeeeeeeeeeeeee (‌Meeeee 88‌).[‌88‌,‌88‌] Meeeeeeeeeeeee eee eeee ee eeeeeeee ee eeee eeee eeeeeeeee ee eeeeeeeeeeeeeeeeeee ee eee eeeeeeeeeeee 8,8-eeeeeeeee-8-eeee.[‌88‌]

‌Meeeee 88‌ 8-Meeeeeeeeee eee 8,8-Meeeeeeeeeeee 8,8-Meeeeeeeeeeee eeee Meeeeee Meeeeeeeeeeeeeeeeeeeeee Meeeeeee Me Meee[‌88‌,‌88‌]

‌Meeeeeeeeee 88‌

e Meeeee M: 8. MMMMM, MMM, −88°M, 8 e; 8. M8M8MM, MMM, −88 ee 8°M. M: MeMMMM, M8, −88°M, 88 eee; 8. M8M8MM, MMM, −88°M ee ee, M: 8. MMMM, MeMe, MMM, 8°M, 88 eee; 8. M8, MMM, −88°M, 88 eee; 8. M8M8MM, MMM, −88°M ee ee.

Meeeeeeeeeee Meeeeeeee

8,8-Meeeeeee-8-eeeeeeeeee-8-eee [‌88‌, M8 = M8 = (MM8)8Me]; Meeeeee Meeeeeeee:[‌88‌]

M 888-eM, eee-eeeeee, eeeee-eeeeeeee eeeee eeeeeeee eeee e eeeeeeee eeeeeeee eee eee e eeeeeeeee, eeeee M8, eee eeeeeee eeee e eeee ee eeeeeee-8-eee (8.88 e, 88 eeee) ee MMM (88 eM). Me8M (88.8 e, 88 eeee) eee eeeee eee eee eeeeeee eee eeeeee ee eeeeee. MMe8 (88 eM, 888 eeee) (MMMMMMM: eeeee) eee eeee eeeee eeeeeeee eeee 8 e (eee eeee eeeeee eeee). Meee MMM (8–8 e) eeeeee eee eeeeeee ee eee eeeeeeee eeeeeeee, eee eeeeeee eee eeeeee ee 8°M eee eeeeeeeeee eeee M8M (88 eM). Mee eeeeeee eeeee eee eeeeeeeee eeee Me8M (8 × 88 eM), eee eeeeeeee eeeeeee eeeeee eeee eeeeee eeee eee. ee MeMMM8 (88 eM) eee eeee eeee eeeee (88 eM). Mee eeeeeee eeeee eee eeeee (MeMM8) eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee ee eeeeeee e eeeee eeeeeee ee eeeeeee eee Me8MM. Mee eeeee eee eeeeee eeeeeee eeeee eeee eeeeeee eee eeeeeeee. Meeee eee eeeeeee ee eee eeeeeee, eee eeeee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeeeee eeeee); eeeee: 8.88 e (88%).

8,8-Meeeeee-8-eeeeeeeeeeee (‌88‌, M8 = Me); Meeeeee Meeeeeeee:[‌88‌]

Me ee eee-eeee eeeeeee eeee ee eeeeeeeeeeee (8.88 e, 88 eeee) eee MMe8 (8.8 e, 88 eeee) ee eeeee MM8Me8 (88 eM) eee eeeee eeee e eeeeeeee eeeeee e eeee ee Me8M (8.8 e, 88 eeee) ee MM8Me8 (88 eM) eeeeee 88 eee. Meee eee eeeeeeee eee eeeeeeee, eee eeeeeee eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee, eee eeee MMMe8 (88 eM) eee eeeee ee eee eeeeeee. Mee eeeeeeeee eeeeeee eee eeeeeeee ee eeeeee Me8MM eeeee eee eeeeee eeee MMMe8 (8.88 eM). Mee eeeeeeee eeeeeeeee eeee eeeeeeeeeeee eeeee eeeeeee eeeeeeee, eee eee eeeee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee/MeMMe 8:8); eeeee: 8.88 e (88%).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8/8e, 888.
• 8.Meeeee-Meee, (8888) M 8, 888.
• 8.Meeeee-Meee, (8888) M 88e8, 8888.
• 8.Meeeee-Meee, (8888) M 88e8, 888.